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authorTejun Heo <tj@kernel.org>2013-01-09 08:05:10 -0800
committerTejun Heo <tj@kernel.org>2013-01-09 08:05:10 -0800
commite71357e118bdd4057e3bc020b9d80fecdd08f588 (patch)
treea26644afeb5efb7dcd5f2e8a59c32c1d509f8574 /block/blk-cgroup.c
parent3c547865902e9fc30dc15941f326fd8039c6628d (diff)
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cfq-iosched: add leaf_weight
cfq blkcg is about to grow proper hierarchy handling, where a child blkg's weight would nest inside the parent's. This makes tasks in a blkg to compete against both tasks in the sibling blkgs and the tasks of child blkgs. We're gonna use the existing weight as the group weight which decides the blkg's weight against its siblings. This patch introduces a new weight - leaf_weight - which decides the weight of a blkg against the child blkgs. It's named leaf_weight because another way to look at it is that each internal blkg nodes have a hidden child leaf node which contains all its tasks and leaf_weight is the weight of the leaf node and handled the same as the weight of the child blkgs. This patch only adds leaf_weight fields and exposes it to userland. The new weight isn't actually used anywhere yet. Note that cfq-iosched currently offcially supports only single level hierarchy and root blkgs compete with the first level blkgs - ie. root weight is basically being used as leaf_weight. For root blkgs, the two weights are kept in sync for backward compatibility. v2: cfqd->root_group->leaf_weight initialization was missing from cfq_init_queue() causing divide by zero when !CONFIG_CFQ_GROUP_SCHED. Fix it. Reported by Fengguang. Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Fengguang Wu <fengguang.wu@intel.com>
Diffstat (limited to 'block/blk-cgroup.c')
-rw-r--r--block/blk-cgroup.c4
1 files changed, 3 insertions, 1 deletions
diff --git a/block/blk-cgroup.c b/block/blk-cgroup.c
index 942f344fdfa7..10e1df9da46e 100644
--- a/block/blk-cgroup.c
+++ b/block/blk-cgroup.c
@@ -26,7 +26,8 @@
static DEFINE_MUTEX(blkcg_pol_mutex);
-struct blkcg blkcg_root = { .cfq_weight = 2 * CFQ_WEIGHT_DEFAULT };
+struct blkcg blkcg_root = { .cfq_weight = 2 * CFQ_WEIGHT_DEFAULT,
+ .cfq_leaf_weight = 2 * CFQ_WEIGHT_DEFAULT, };
EXPORT_SYMBOL_GPL(blkcg_root);
static struct blkcg_policy *blkcg_policy[BLKCG_MAX_POLS];
@@ -710,6 +711,7 @@ static struct cgroup_subsys_state *blkcg_css_alloc(struct cgroup *cgroup)
return ERR_PTR(-ENOMEM);
blkcg->cfq_weight = CFQ_WEIGHT_DEFAULT;
+ blkcg->cfq_leaf_weight = CFQ_WEIGHT_DEFAULT;
blkcg->id = atomic64_inc_return(&id_seq); /* root is 0, start from 1 */
done:
spin_lock_init(&blkcg->lock);